Research goals in the next year of this project are: 1. Develop a stable electrode for creatinine in serum using immobilized creatininase (EC 3.5.4.-). The enzyme will be purified of all urease and creatinase activity, and bound to a gas NH3 membrane sensor. 2. To develop specific electrode for nitrite ion based on an NAD linked enzyme from bacteria. 3. To develop a practical, easily manufacturable enzyme electrode for glucose and urea based on a technique of precasting sheets of immobilized enzymes.